1. Field of the Invention
The present invention relates to a linear guide used in the field of, for example, industrial machines, such as machine tools and injection molders.
2. Description of the Related Art
For instance, an apparatus shown in FIG. 7 is known as a related linear guide.
This linear guide has a guide rail 1 extending in an axial direction, and a slider 2 laid across the guide rail 1 so as to relatively move on the guide rail 1 in the axial direction.
Rolling element rolling grooves 3 extending in the axial direction are formed on each of both side surfaces of the guide rail 1. Rolling element rolling grooves 7 respectively opposed to the rolling element rolling grooves 3 are formed on each of the inner side surfaces of both sleeve portions 4 of the slider main body 2A of the slider 2. Many balls B as one example of rolling elements are rotatably  mounted between these opposed rolling element rolling grooves 3 and 7. The slider 2 can be relatively moved along the axial direction on the guide rail 1 through the rolling movements of the balls B.
As this movement of the slider 2 is made, the balls B interposing between the guide rail 1 and the slider 2 roll and axially cove to an end portion of the slider 2. However, it is necessary to indefinitely circulate the balls B so as to continuously move the slider 2 in the axial direction.
Thus, a rolling element passage 7 axially extending through the interior of the sleeve portions 4 of the slider main body 2A is formed. For example, an end caps 5 approximately formed in a U-shaped is fixed to each both ends of the slider main body 2A through a fixing means such as a screws 12, etc. A direction changing passage 10 curved in an semi-arc and shape and communicating the rolling element passage 8 and each of a portion between both the above rolling element rolling grooves 3 and 7 is formed in each of the end caps 5. Thus, a rolling element endlessly-circulating raceway is formed. Incidentally, in FIG. 7, reference numeral 11 designates a side seal fixed to an end surface of the slider main body 2A together with the end cap 5 through a screw 12. Reference numeral 10 denotes a tap hole formed in an end surface of the slider main body 2A and adapted so that a screw 12 is screwed thereinto. Reference numeral 13 designates a grease nipple. Reference numeral 14 denotes a bolt insertion hole used for fixing the guide rail 1.
Also, there has been proposed an apparatus configured so that a separator 20 is interposed between adjacent balls B, as shown in FIG. 8, so as to prevent the balls, which endlessly circulate, from being in contact with each other and as to improve operability by applying an appropriate compressing force to rows of balls, and so that a predetermined clearance is provided between one of balls B of one row, which endlessly circulate, and a separator 20 (See, for example, JP-A-2000-213538).
The separator 20 is made of a material, which excels in injection-moldability and wear-proof, for example, “66 nylon” and is shaped like a short cylinder. A concave surface 21 having a curvature radius corresponding to the absolute value of the curvature radius of an outer peripheral surface of the ball B is provided in each of both end surfaces of the separator 20.
Meanwhile, as can be understood from FIGS. 8A and 8B, the dimension of the clearance provided between the ball B, which endlessly circulates, and the separator 20 varies according to the phase of the ball B. In the apparatus disclosed in JP-A-2000-213538, the short-cylindrical separator 20 is only interposed between the balls B. The orbital motion of the separator 20 in the load raceway, the direction changing passage 6 and the rolling element passage 8 in the slider 2 is supported only by the balls B. Thus, in a case where the dimension of the clearance is too large, the separator 20 itself does not have self-sustainability (or attitude stability). Consequently, the separator 20 may be toppled in the arc-like direction changing passage 6, as shown in FIG. 9. In this case, the orbital motion of the separator 20 together with the balls B is disturbed, so that poor circulation is caused. Thus, components of the direction changing passage 6 formed of a resin may be damaged. Consequently, it is necessary to adjust the clearance dimension in units of 0.1 mm so as to prevent the separator 20 from being toppled.
This causes the necessity for preparing a plurality of separators 20, which differ in axial dimension from one another, and for fabricating the apparatus by replacing the separators 20 several by several separators, which differ in dimension from one another, to thereby adjust the clearance dimension. Consequently, it takes time to fabricate the related apparatus, and the cost thereof is high.